Regarding ATPL issue and P1/S...
When I went to the CAA FCL dept to get my ATPL issued I didn't claim any of my hours with the airline as P1/S as I had no signatures. I had enough P1 from other means not to need it and had assumed "no signature = P1/S". So all my airline time was claimed P2. The chap at the desk took one look at the hours and told me that since it was airline time at least half must be P1/S and crossed through the P2 figure on the form, halved it and added it to my P1 time. He said that if necessary for bods with low P1 hours they will just get a fax from your airline to confirm that you've been flying that type multi-crew. Others from my company who've been through since have done just that.